The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Known powertrain architectures include torque-generative devices, including internal combustion engines and electric machines, which transmit torque through a transmission device to an output. The output is operatively connected to a driveline for a motor vehicle. One exemplary powertrain includes a two-mode, compound-split, electro-mechanical transmission which utilizes an input member for receiving motive torque from a prime mover power source, preferably an internal combustion engine, and an output member for delivering motive torque from the transmission to the vehicle driveline. Electric machines, operable as motors or generators, generate a torque input to the transmission, independently of a torque input from the internal combustion engine. The electric machines may transform vehicle kinetic energy, transmitted through the vehicle driveline, to electrical energy potential that is storable in an electrical energy storage device. A control system monitors various inputs from the vehicle and the operator and provides operational control of the powertrain system, including controlling transmission operating state and gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange between the electrical energy storage device and the electric machines. A control system monitors various inputs from the vehicle and the operator and provides operational control of the powertrain system, including controlling transmission operating state and gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange between the electrical energy storage device and the electric machines. Known system torques that can vary during powertrain operation include hydraulic pumps supplying pressurized hydraulic fluid to actuate various clutch devices in the transmission and provide system cooling. Known transmission gears and other rotating components generate momentums and inertias which affect torque output. Known electrically-powered accessories generate varying electrical loading which affect operation.
Known control systems monitor various inputs from the vehicle and the operator and provide operational control of the powertrain system, including controlling transmission operating state and gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange between the electrical energy storage device and the electric machines. Known control systems for hybrid powertrains interactively control the internal combustion engine and the electric machines to transmit mechanical torque and electric power to meet an operator torque request for tractive torque. Such systems act to simultaneously optimize vehicle fuel economy, minimize vehicle exhaust emissions, and meet design life goals for an electric energy storage device, e.g., a high voltage battery pack, and take into consideration other requirements related to driveability, system robustness, and accessory loading. The systems operate by accurately measuring vehicle load demands, determining the capability of the energy storage devices, determining desired propulsion system operating conditions for optimal fuel economy, and implementing the desired propulsion system operating conditions.
A powertrain may have a need for service, including diagnostic analysis related to vehicle operation and engine operation. Operation of the engine independently of the hybrid powertrain is useful during diagnostic analysis in order to identify and isolate a fault and verify any subsequent repair.